Crystal Structure and Chemical Composition of Ludwigite from Vranovac Ore Deposit (Boranja Mountain,Serbia)

作     者：Pavle TANCIC Radovan DIMITRIJEVIC Maja POZNANOVIC Aleksandar PACEVSKI Slobodanka SUDAR 

作者机构：Geological Institute of Serbia Faculty of Mining and GeologyDepartment of Mineralogy and Crystallography 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2012年第86卷第6期

页      面：1524-1538页

核心收录：

学科分类：0709[理学-地质学] 0819[工学-矿业工程] 081704[工学-应用化学] 081803[工学-地质工程] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0816[工学-测绘科学与技术] 0703[理学-化学] 070301[理学-无机化学] 

主　　题：ludwigite crystal structure chemical composition M-O distances distortion parameters,ions valences comparison formation temperature 

摘      要：The crystal structure of ludwigite from Vranovac ore deposit （Boranja Mt., Serbia） was refined using the X-ray powder diffraction （XRPD） Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of： a=9.2515（2） A; b=12.3109（2） A; c=3.03712 （7） A; and V=345.91（1） A3. The calculated distances and angles are mostly in good agreement with the Mg2＋-Fe2＋ substitutions across the M（1） and M（3） sites, as well as with the Fe3＋-AI3＋ replacement in the M（4） site. However, the mean observed M（2）-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3＋ content in the M（2） site. Such replacement was compensated by slight increase of the Fe2＋ content in the M（4） site, resulting in the （Mg1.4sFe2＋o.46Fe3＋***.o2）2.o1 （Fe3＋o.94Fe2＋0.04Al0.02）1.00B1.00Os composition. The formation temperature was estimated to be about 500- 600C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M（3） and M（4） sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.